Date: Thu, 02 Apr 1998 21:22:03 -0600 From: David Kelly <dkelly@hiwaay.net> To: joelh@gnu.org Cc: freebsd-chat@FreeBSD.ORG Subject: Re: Crimping SCSI cables Message-ID: <199804030322.VAA15771@nospam.hiwaay.net> In-Reply-To: Message from Joel Ray Holveck <joelh@gnu.org> of "Thu, 02 Apr 1998 12:51:02 EST." <199804021751.MAA27480@mescaline.gnu.org>
next in thread | previous in thread | raw e-mail | index | archive | help
Joel Ray Holveck writes: > I am using an AHA-1542C host adapter. This adapter, I am told, is > very sensitive to cabling problems. I need a SCSI cable with all 8 > connectors, but haven't seen any in what I would consider a reasonable > price range (most are >$80 or so). Does anybody know if I should > expect a problem if I crimp my own? I have not observed my 1542CF was all that sensitive to cabling. Your 1542C? Not CF? Not "Fast"? Then at 5 MHz SCSI bus speed it would be comparably immune to lots of the nasty stuff that bites others. "Active Termination" cures lots of ills. I make my own cables all the time. Keep meaning to buy the special tool, as even the stamped steel made-in-China $30 cheapie tool works better than a cast iron vice. And its easier to carry around. :-) Use wood blocks in the vice, you don't want the vice's teeth biting into your plastic connector. Generally there is a triangle on the insulation-displacement connector (IDC) indicating where pin 1 is. Triangle goes nearest the red stripe on your cable. Actually it doesn't matter as long as you do the same thing everywhere along the cable. Some IDC connectors have a keying tab in the middle on one side. That's a good thing, look for it when you buy. As long as all your connectors are on the cable right, that tab will/should prevent you from connecting the cable to your devices wrong. I have purchased ribbon cable which was (no longer?) the correct width, it was too narrow. If your cable isn't the right width then the penetrations from the IDC will not straddle the wires. Not only will some connections not make, other wires will short. Spend plenty of time verifying each and every wire in the cable is aligned with the sharp things in the connector. Generally the backing plastic has a grove for each ribbon wire too. The Really Good IDC connectors have an adhesive strip in the plastic backing plate. "Stick" your cable to the backing and get it aligned there first, then the alignment with the sharp metal points goes much easier. Apply a little force to load the connector and cable so they don't move. Then check alignment one last time before clamping down with force. Doesn't it sound awful? All this for $2 connectors and $1/foot cable. Pre-built cables are often $3 to $5 (cheaper than I can buy the parts). The problem is, I can make my own internal SCSI cable that fits exactly, rather than make do with pre-built cables. -- David Kelly N4HHE, dkelly@nospam.hiwaay.net ===================================================================== The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199804030322.VAA15771>